Physalaemin-like immunoreactive material (PHLIM) is a relatively prominent rabbit stomach macromolecule which has properties of mucin; it is assumed to possess the N-terminal amino acid sequence which was found in PHLIP-8 (<Glu-Val-Asp-Pro-Asn-Ile-Gln-Ala-OH). Our proposal to determine whether a high specific activity analog of physalaemin may exist in the central nervous system (perhaps, in precursor form as a component of a glycoprotein) has yet to be performed because of difficulties in obtaining a high titer antiserum. An attempt will be made to obtain a mouse monoclonal antibody in order to determine whether distribution of a PHLIP-8 precursor in the central nervous system will provide immunohistochemical confirmation of prior observations obtained in this laboratory using polyclonal antisera to physalaemin. This investigation also has implications relative of oat cell carcinoma (which contains a physalaemin-related peptide) and to diseases involving glycoproteins in the mammalian digestive and respiratory tracts.